vadorovsky / network-types

Rust structs representing network-related types (on Layer 2, 3 and 4)

network-types

Rust structs representing network protocol headers (on Layer 2, 3 and 4).

The crate is no_std, which makes it a great fit for eBPF programs written with Aya.

Examples

An example of an XDP program logging information about addresses and ports for incoming packets:

use core::mem;

use aya_ebpf::{bindings::xdp_action, macros::xdp, programs::XdpContext};
use aya_log_ebpf::info;

use network_types::{
    eth::{EthHdr, EtherType},
    ip::{Ipv4Hdr, Ipv6Hdr, IpProto},
    tcp::TcpHdr,
    udp::UdpHdr,
};

#[xdp]
pub fn xdp_firewall(ctx: XdpContext) -> u32 {
    match try_xdp_firewall(ctx) {
        Ok(ret) => ret,
        Err(_) => xdp_action::XDP_PASS,
    }
}

#[inline(always)]
unsafe fn ptr_at<T>(ctx: &XdpContext, offset: usize) -> Result<*const T, ()> {
    let start = ctx.data();
    let end = ctx.data_end();
    let len = mem::size_of::<T>();

    if start + offset + len > end {
        return Err(());
    }

    Ok((start + offset) as *const T)
}

fn try_xdp_firewall(ctx: XdpContext) -> Result<u32, ()> {
    let ethhdr: *const EthHdr = unsafe { ptr_at(&ctx, 0)? };
    match unsafe { *ethhdr }.ether_type {
        EtherType::Ipv4 => {
            let ipv4hdr: *const Ipv4Hdr = unsafe { ptr_at(&ctx, EthHdr::LEN)? };
            let source_addr = unsafe { (*ipv4hdr).src_addr };

            let source_port = match unsafe { (*ipv4hdr).proto } {
                IpProto::Tcp => {
                    let tcphdr: *const TcpHdr =
                        unsafe { ptr_at(&ctx, EthHdr::LEN + Ipv4Hdr::LEN) }?;
                    u16::from_be(unsafe { (*tcphdr).source })
                }
                IpProto::Udp => {
                    let udphdr: *const UdpHdr =
                        unsafe { ptr_at(&ctx, EthHdr::LEN + Ipv4Hdr::LEN) }?;
                    u16::from_be(unsafe { (*udphdr).source })
                }
                _ => return Ok(xdp_action::XDP_PASS),
            };

            info!(&ctx, "SRC IP: {:i}, SRC PORT: {}", source_addr, source_port);
        }
        EtherType::Ipv6 => {
            let ipv6hdr: *const Ipv6Hdr = unsafe { ptr_at(&ctx, EthHdr::LEN)? };
            let source_addr = unsafe { (*ipv6hdr).src_addr.in6_u.u6_addr8 };

            let source_port = match unsafe { (*ipv6hdr).next_hdr } {
                IpProto::Tcp => {
                    let tcphdr: *const TcpHdr =
                        unsafe { ptr_at(&ctx, EthHdr::LEN  + Ipv6Hdr::LEN) }?;
                    u16::from_be(unsafe { (*tcphdr).source })
                }
                IpProto::Udp => {
                    let udphdr: *const UdpHdr =
                        unsafe { ptr_at(&ctx, EthHdr::LEN + Ipv6Hdr::LEN) }?;
                    u16::from_be(unsafe { (*udphdr).source })
                }
                _ => return Ok(xdp_action::XDP_PASS),
            };

            info!(&ctx, "SRC IP: {:i}, SRC PORT: {}", source_addr, source_port);
        }
        _ => {},
    }

    Ok(xdp_action::XDP_PASS)
}

Naming conventions

When naming stucts and fields, we are trying to stick to the following principles:

• Use CamelCase, even for names which normally would be all uppercase (e.g. Icmp instead of ICMP). This is the convention used by the std::net module.
• Where field names (specified by RFCs or other standards) contain spaces, replace them with _. In general, use snake_case for field names.
• Shorten the following verbose names:
  • source -> src
  • destination -> dst
  • address -> addr

Feature flags

Serde support can be enabled through the serde feature flag. It is intended to be used with binary serialization libraries like bincode that leverage Serde's infrastructure.

Note that no_std support is lost when enabling Serde.

License: MIT

network-types's Issues

Add a method to ipv4 to recalculate the checksum

Hi,

It would be great to have some helper function to recalculate the ipv4 checksum, in case some fields got updated.

Thanks

Add ARP packet header

add missing L4Protocol values for IPv6 extension headers

I believe a few values for IPv6 extension headers [1] are missing in the current L4Protocol https://docs.rs/network-types/0.0.1/src/network_types/l4/mod.rs.html#7-39 values and can be added. (For reference, the full list of the "Assigned Internet Protocol Numbers": https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml)

[1] https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml